|
ENVIRONMENTAL HEALTH DEPARTMENT
<br /> oAc1.0?N o
<br /> SAN JOAQUIN COUNTY
<br /> Donna K.Heran,R.E.H.S. Unit Supervisors
<br /> 304 East Weber Avenue Third Floor Car[Borgman,R.E.H.S.
<br /> Director Mike Huggins,
<br /> AI Olsen,R.E.H.S. Stockton, California 95202-2708 R.E.H.S.,R.D.I.
<br /> • e .• L• Pro rain Manager Douglas W.Wilson,R.E.H.S.
<br /> Telephone: 209 46$-3420
<br /> Laurie A..Cotulla,R.E.H.S. p ( ) Margaret Lagorio,R.E.H.S.
<br /> Program Manager Fax: (209) 464-0138 Robert McClellon,R.E.H.S.
<br /> Mark Barcellos,R.E.H.S.
<br /> MIKE STRONG f,j FIAR 11 2005
<br /> RUTH STRONG,PlfOPERTY
<br /> 3 3 0 E HOL'1�00D
<br /> TRACY,-& 95376
<br /> RE: RUTH STRONG PROPERTY
<br /> 5157 W BUSINESS LOOP 205
<br /> TRACY CA 95376
<br /> Four groundwater monitoring wells,MW8, MW9,MkX711, and NAV12, have been installed in the
<br /> downgradient direction (fluctuating between northeast to northwest) of the three wells NAV2,MWS,
<br /> and NRV6 to define the lateral extent of the groundwater contamination. San Joaquin County
<br /> Environmental Health Department (El-ID) has reviewed Third Quarter2004 Quarler) Report(the
<br /> report) dated December 23,2004 prepared by Advanced GeoEnvironmental, Inc. (AGE), and a fax
<br /> copy of the analytical results of the groundwater samples for 4,h quarter 2004. Analytical results of
<br /> the water samples from all 4 downgradient wells MW8, i RV9,MW11, and 1\1 X712 were non-detect
<br /> for all contaminants the last four quarters.
<br /> In a telephone conversation with AGE on March 9, 2005, EHD agreed that the extent of the
<br /> contamination at the above-referenced site has been defined. Submit a Problem Assessment Report
<br /> (PAR) to EHD by April 30,2005. The PAR should include a site conceptual model which describes
<br /> the lateral and vertical extent of the contamination,identification of at least two remedial alternatives,
<br /> and a proposal for investigating the remedial alternatives so the most cost-effective alternative to
<br /> clean up the site can be evaluated.
<br /> During the telephone conversation mentioned above,AGE suggested soil vapor extraction and air
<br /> sparge as one of the technologies to be evaluated in the PAR. According to the well logs of NM2,
<br /> MW5, and MW6,a clay to silty clay layer begins between 10 feet to 15 feet below surface grade (bsg),
<br /> and the average depth to groundwater(M\V5)is at about 13 feet bsg over the last 5 years. Due to
<br /> the presence of clay soil,lack of a vadose zone,and low concentration of aromatic hydrocarbons in
<br /> the groundwater,soil vapor extraction and air sparging are unlikely to work. EHD recommends
<br /> evaluating soil removal as one the potential remediation alternatives. Analytical results of the soil
<br /> samples from NRV6 taken at 15 feet bsg in May 2000 were 330 milligrams per kilogram (mg/kg) of
<br /> Total Petroleum Hydrocarbon as diesel (TPH-d) and 140 mg/kg of TPH-gasoline (IPH-g). Results
<br /> of the soil samples taken from MW2 at 15 feet bsg were 380 mg/kg of TPH-g and 3.9 mg/kg of
<br /> Benzene. Removal of contamination source in the soil may reduce the contamination concentration
<br /> in groundwater,and bring the site toward closure status in a timelier basis. If you have any
<br /> questions,please direct them to Jeff Wong at (209) 468-0335.
<br /> Donna Heran,RENS,Director
<br /> Environmental Health Division
<br /> Jeffrey Wong, REHS C7 Margaret agorto,REHS
<br /> LOP/Site Mitigation Unit IV Supervisor
<br /> c: Advanced GeoEnvironmental Inc. —Brian Millman
<br /> c: RWQCB,Central Valley Region—James L.L. Barton,RG
<br />
|